<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../js/vue.js"></script>
</head>

<body>
    <div id="app">
        ￥<input v-model="china" type="text"><br>
        $ <input v-model="america" type="text"><br>
        {{china+'人民币='+america+'美元'}}
    </div>
</body>
<script>
    var vue = new Vue({
        el: '#app',
        data() {
            return {
                china: '',
                america: '',
            
            }
        },
        watch: {
            china: function (newValue, oldValue) {
                this.america = newValue * 0.1427
                
            },
            america: function(newValue,oldValue){
                this.china = newValue/0.1427
            }
        }
    })
</script>

</html>